Cambodia's ruling Cambodian People's Party (CPP), led by long-time Prime Minister Hun Sen, has won all parliamentary seats in last month's largely unopposed general election, according to electoral officials.
The CPP won in all 25 provinces and cities, Sik Bun Hok, chairman of the National Election Committee (NEC), said in a statement on Wednesday.
Hun Sen, who has led Cambodia for 33 years and said he wants to hold office for at least another 10, campaigned on promises of continued economic development, peace and stability.
But rights groups said the July 29 vote was neither free nor fair given the absence of a significant challenger to the prime minister.
Critics had condemned the vote as illegitimate and called for a boycott following the dissolution of the largest opposition political force - the Cambodia National Rescue Party (CNRP) - and a government crackdown against dissent.
The CPP pointed to 83 percent voter turnout as evidence that a boycott by the opposition failed, but allegations of voter intimidation and some 600,000 spoiled ballots undermined the claims.
Observers said that problems of credibility could trail the new government, which will be formed on September 5.
"It's like pushing a cart uphill," independent political analyst Meas Ny to AFP news agency.
"From now on, the new government will be under attack and defending itself."
The CNRP, the only viable opposition party which almost won in 2013, was disbanded last year by the Supreme Court and 118 of its members were banned from politics for five years.
CNRP leader Kem Sokha was jailed on treason charges in September. He remains in pre-trial detention.
Opposition figures also doubt the claimed high turnout, saying they would ramp up efforts to try to advocate with governments abroad.
"The CPP is leading the nation to a one-party state with one man making all decisions for the entire nation through a sham election rejected by democratically elected governments," Mu Sochua, CNRP's vice president who lives in self-imposed exile abroad, told Reuters news agency.
"Sham elections cannot produce a legitimate National Assembly," she said.
Hun Sen is one of the longest-serving rulers in the world.
The 66-year-old helped bring roads to a country affected by decades of civil war and the Khmer Rouge regime, which killed a quarter of the Cambodian population from 1975 to 1979.
A former commander in the group, he defected and was installed as prime minister in 1985 at the age of 32, later presenting himself as a saviour while warning of conflict if his time in office ends.
The message has resonated with segments of society.
Western governments pulled funding for the vote and condemned it as not credible, but China, which has provided loans to Cambodia, remained silent on human rights issues.
The CPP has long dominated Cambodia but the CNRP, which was founded in 2012, capitalised on discontent with corruption and inequality.
It earned 44 percent of the vote in 2013 and took home a similar amount in local 2017 elections.
The United States, which already imposed visa curbs on some Cambodian government members close to Hun Sen over the crackdown, said it would consider steps, including an expansion of visa restrictions, in response to July's "flawed election."